Cinnamon leaves are called for fairly commonly in Indian dishes, including desserts. They also have many names: they are known as tejpat leaves in parts of India and are sometimes called Malabar Leaves, Malabathrum, and (most frequently) Indian Bay Leaves. This last one is because cinnamon leaves look similar to bay leaves and both come from a species of laurel tree (though neither is the exact same tree that we get cinnamon bark from).
Cinnamon leaves and bay leaves are also used in the same way – simmered in long-cooked dishes and removed before eating. However, cinnamon leaves have a very different flavour from bay leaves. They taste like cloves and cinnamon with citrus undertones. In fact, if you don’t have cinnamon leaves for a recipe, it’s better to substitute a clove and a small piece of cinnamon than a regular bay leaf.